1. Field Of The Invention
This invention relates in general to an apparatus for controlling the fuel economy of a vehicle and in particular to an apparatus which indicates the efficiency of acceleration of the vehicle and can be adapted to automatically control the vehicle acceleration.
2. Description Of The Prior Art
Early devices for indicating the efficiency of automotive vehicles were mechanical controls having a number of interrelated moving parts. One such device has been disclosed in U.S. Pat. No. 1,595,960, issued Aug. 10, 1926 to James M. Brown and entitled "Efficiency Indicator For Automotive Vehicles". This patent discloses a device which measures both the grade being tranversed by the vehicle and the position of the engine throttle. These two measurements are combined to indicate the speed the vehicle should be traveling under normal conditions. If this speed is different from that indicated by the speedometer, the vehicle is operating below its normal efficiency and should be examined for defects. However, the mechanical linkages associated with this device requires careful adjustments in order to obtain accurate measurements. Furthermore, this device can only indicate the efficiency of a vehicle if the vehicle is traveling at a constant velocity. During periods of vehicle acceleration, the operator would not be aware of the efficiency of the vehicle.
Other devices have been utilized to indicate the efficiency of the vehicle by monitoring the engine's fuel consumption. These devices provide the vehicle operator with a fuel economy measurement such as miles per gallon. Hence, the higher the miles per gallon measurement, the greater the efficiency of the vehicle. However, because the fuel flow in the monitored fuel line does not change instantaneously with the throttle position, these devices cannot effectively measure the efficiency of acceleration of the vehicle. Thus, these devices provide accurate measurements only when the vehicle is operating at a constant velocity.